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The Bogie suspensions ensure better stability at higher loads and also give the utmost reliability under extreme climatic conditions with minimum maintenance. Many vehicle manufactures have adopted for the bogie suspension at rear based on its advantages. The noises generated from the vehicle in the field includes engine noises and flow noises and hence it is very difficult to clearly discern the noise generated from suspension system of the vehicle [1]. Most suspension system noises do not come from a single part but they are caused by the coupling action between related parts, making it difficult to clearly identify the exact cases. This paper details the overall approach to identify the bogie suspension noise on a commercial vehicle and countermeasures to reduce the same.

Driver fatigue is one among the important factors for accidents, causing loss of precious life and property. Apart from long driving hours, driver fatigue can be due to poor ride quality, cabin noise, high vibration levels and poor ergonomics. In last few years, there has been enough emphasis to improve the noise and vibration comfort of commercial vehicles, which is governed by vibration levels at tactile points such as steering wheel, gear lever, pedal and seat. Steering wheel vibration is an important element which driver uses to express about the vehicle vibration quality. Design of steering system is driven by ergonomics, packaging, durability, safety, vibration & ride and handling requirements. This paper discusses about methodology of steering assembly development for Noise Vibration and Harshness (NVH) performance of commercial vehicle.

Commercial vehicle NVH attributes primarily focus on interior noise for driver's comfort and exterior noise for environmental legislation. Major sources for both the interior and exterior noise are power train unit, exhaust and air intake system. This paper focuses on development of Air Intake System (AIS) for better interior and exterior NVH performance for medium and heavy commercial vehicles. For air intake system, structural radiations from its panels and nozzle noise are significant contributors on overall vehicle NVH. Noise generation mechanism in air intake system occurs due to opening and closing of the valves and inlet air column oscillation by sharp pressure pulse from cylinder. Based on benchmarking, vehicle level targets have been arrived, and then cascaded to system and sub-system level targets. For air intake system, targets for nozzle noise at wide open throttle condition have been set for exterior NVH performance.